COMPARATIVE EFFECT OF ONE SYNTHETIC BIOSTIMULANTS AND MICROBIAL BIOSTIMULANT (Azospirillum lipoferum) ON YIELD AND QUALITY OF WASHINGTON NAVEL ORANGE FRUITS.

Abstract

Foliar sprays with synthetic biostimulants or microbial biostimulants PGPR (plant growth promoting rhizobacteria) were used. They contain amino acids, macro and micro elements, humic acid and vitamins. Also its direct effect in release stimulants, nutrients, antibiotics, biosides and sidrofores or activation of these microorganisms in plant rhizosphere in activation and improving plant growth. This study was carried out during 2013 and 2014 seasons on 10 years old Washington navel orange (Citrus sinensis Osbeck) trees budded on sour orange (Citrus aurantium L.) rootstock, grown in a private orchard located at Motobus, Kafr El Sheikh Governorate, to study the effect of synthetic stimulants (Furdose) and microbial biostimulant (Azospirillum lipoferum)on fruit set, dropping, yield and fruit quality. Furdose as a commercial synthetic biostimulant and microbial biostimulant Azospirillum lipoferum were used as foliar application alone or in combination at two stages, before flowering(first mach) or after fruit set(first may) or before flowering and after fruit set. The obtained results revealed that, fruit set and drop percentages, yield and fruit quality were u significantly affected by Furdose and Azospirillum lipoferum treatments alone or in combination in both seasons. The data cleared that, both stimulators enhanced fruit set percentage, yield and fruit quality of Washington navel orange trees. Azospirillum lipoferum alone or combined with Furdose was more effective on improving the productivity and fruit quality .The T6 (foliar spray of A. lipoferum after fruit set) , T7 ((foliar spray of A. lipoferum before flowering and after fruit set) and T10 (foliar spray of Furdose plus A. lipoferum before flowering and after fruit set) were the most effective treatments on yield and fruit quality. It increased fruit set, yield and fruit quality in terms of fruit number, fruit kg/tree, fruit firmness, soluble solids content, reducing and total sugars and vitamin C. Fruit drop was decreased without significant differences among them in both seasons. Thus spraying with Azospirillum lipoferum after fruit set T6 (foliar spray of A. lipoferum after fruit set)) gave 112.4 and 115.7 kg/tree compared with T7 (foliar spray with Azospirillum lipoferum before flowering and after fruit set) 108.7 and 121.4 kg/tree and T10 ((foliar spray the combination of them before flowering and after fruit set) 114.7 and 130.3 kg/tree during both seasons, respectively. The use of (Azospirillum lipoferum) is recommended for increasing fruit yield and quality such as firmness, SSC, V.C and total sugars which may be increase the fruit ability to handling stages and longest shelf life, and gave the highest of net return per feddan and the increase in net return over control. when used alone or with synthetic biostemulants (Furdose) compared with the use of synthetic biostemulants (Furdose) alone .